Droplet actuators are used to conduct a wide variety of droplet operations. A droplet actuator typically includes two plates separated by a gap. The plates include electrodes for conducting droplet operations. The space is typically filled with a filler fluid that is immiscible with the fluid that is to be manipulated on the droplet actuator. The formation and movement of droplets is controlled by electrodes for conducting a variety of droplet operations, such as droplet transport and droplet dispensing. When a protocol requires the use of beads, such as magnetic beads, it may be useful to retain the beads in a particular location within the droplet actuator, rather than allowing the beads to move freely throughout the droplet actuator and, therefore, there is a need for alternative approaches to manipulating beads in a droplet actuator.